Insulated utility constructions



Jan. 14, 1969 Filed June 28, 1965 M- D. OOSTERBAAN INSULATED UTILITYCONSTRUCTIONS Sheet Dec. A964 Jan. I965 Feb/965 m 20 /0 20 /0 20 60 E L\Q 20 s A m k 0 =50 f/om o/sewer O Top of sewer '4 fie/ow sfyrofoam A"Above .s/yro/am I N VENTOR.

Marv/h 0, Oasferb 00/7 Vkv/ ' QTTORNE Y5 1969 M. 0. OOSTERBAAN INSULATEDUTILITY CONSTRUCTIQNS Sheet' Filed June 28, 1965 II II II In II ll l| III I INVENTOR. Mar //7 0. 006 749/6000 a6 (Mi, WTORA/fh? United StatesPatent Oflice 3,421,328 Patented Jan. 14, 1969 3,421,328 INSULATEDUTILITY CONSTRUCTIONS Marvin D. Onsterbaan, Sanford, Mich., assignor toThe Dow Chemical Company, Midland, Mich., a corporation of DelawareFiled June 28, 1965, Ser. No. 467,508

U.S. Cl. 6172.1 Int. Cl. F16l1/00;E03b 7/12 4 Claims ABSTRACT OF THEDISCLOSURE This invention relates generally to underground thermalinsulation of utilities. More particularly, the invention concerns anovel construction providing high insulating properties, with respect tofrost penetration, for utilities such as sanitary sewer lines.

To protect sanitary sewers and similar utility constructions whereinwater and other freezable components are conveyed, it has generally beennecessary to install them beyond the depth of frost penetration. Usuallyin the United States, this has required an excavation of some five tosix feet into the soil or rock. In Canada or in extremely frigid areasof the United States it has not been unusual to go as deep as eightfeet. Likewise, where already existing installations of utilities hadinitially been located at a proper depth to prevent frost penetration,later excavations over these installations, such as might be required byurban renewal projects or highway construction, would often remove asubstantial portion of the soil above the utilities and thus subjectthem to freezing during winter months.

Accordingly, this invention presents a utility construction wherein thedepth of earthen materials above the utility installation or line, ifany, need only be a fractlon of that which was heretofore required underusual conditions of frost penetration.

Briefly then, the concept of the present invention evolves about theplacing of a layer of plastic foam material having high insulatingproperties above the utility line as a barrier to frost penetrations,thus eliminating the necessity of placing utility lines and the like atsubstantial depths below the soil surface.

Yet additional advantages of the present invention, and its numerouscognate benefits and features are even more apparent and manifest in anyby the ensuing descr ption taken in conjunction with the accompanyingdrawing in which, wheresoever possible, like characters of referencedesignate corresponding material and parts throughout the several viewsthereof, in which:

FIGURE 1 is a fragmentary plan view of a highway slip ramp constructionover a utility line, which construction embodies the concepts of thepresent invention;

FIGURE 2 is an enlarged fragmentary cross-sectional view thereof takengenerally along the reference line 2-2 of FIG. 1;

FIGURE 3 is a greatly enlarged fragmentary crosssectional view thereoftaken generally along the reference line 3-3 of FIG. 1; and

FIGURE 4 is a graphical representation of the effects construction ofFIG. 1 during a typical winter season.

The highway slip ramp 10 of the drawing is comprised of a highway pavingmaterial 11, such as cement or asphalt, located over a vitrified claysanitary sewer pipe line 12, which sewer line is at some depth below thesurface of soil or earthen material 14. This arrangement illustrates anactual construction wherein the principles of the present invention wereemployed to overcome certain problems which will become more evidenthereinafter.

Before slip ramp 10 was constructed, sewer line 12 had been installed ata sufiicient depth below soil 14 to prevent frost from penetrating tothe sewer line 12. In the region in which the sanitary sewer line 12 wasinstalled, this was a depth of over five feet. When necessity requiredthe construction of a highway in this area, an excavation for slip ramp10 was made over the sewer line 12, which excavation resulted in thesanitary sewer line 12 being left at only about two and one-half feetbelow the final grade. Without the concept of the present invention,this situation would have required the expensive and time-consumingoperation of lowering the entire sewer line to its original depth toprevent dam-aging frost penetration into the sewer line.

However, following the principles of this invention, a continuous areasome one hundred feet long and ten feet wide was excavated to about sixinches above the sewer line 12. Then eight foot long boards of one inchthick expanded polystyrene, such as produced by The Dow Chemical Companyunder the trademark Styrofoam, were placed crosswise to the sewer line12 in this area as illustrated in FIG. 3. The boards formed twocontinuous layers 16 and 18 providing a two inch thickness of insulatingmaterial between the soil-roadway surface and the sewer line 12. Therethen remained only about two feet of soil 14 between the pavement of theslip ramp 10 and the top of the insulating layers 16 and 18. In thisconstruction, the minimum temperature realized just beneath theinsulating layers was recorded (FIG. 4) as 32 F. while the temperaturesat the top and bottom of the sewer line were recorded at that time as 37F. and 47 B, respectively. At no time during the recording was the pipeline subjected to freezing temperatures, there being a frost-free zonecompletely about the pipe line during the given degree-day environmentinvolved in this construction.

In addition to the embodiment of FIGS. l-3, it should also be obviousthat initial insulation of utility lines carrying freezable fluids, aninsulating barrier, such as expanded polystyrene, over such lines wouldsubstantially reduce the excavation depth required to install suchutilities. Also, it is conceivable that with the proper foam thickness ahighway paving material such as asphalt or concrete can be placeddirectly on the insulating barrier material. Thus, the present inventionshould be comprehended in all of its alternative embodiments and shouldnot be limited by the specific embodiments heretofore described.

With regard to the insulating barrier itself, it should be furtherunderstood that other expanded plastic materials having similarqualities of insulation, heat capacity, imperviousness to vaportransport, compressibility, strength and thermal conductivity asexpanded polystyrene and also contemplated as being included as workablein constructions of the present invention. One of such other possiblelayer materials can be closed cell expanded urethane, for example. It isfurther conceivable that the barrier can take on an inverted] U-shapedconfiguration providing a tunnel effect over a utility line.

Accordingly, what is claimed as new is:

1. In a construction for carrying a freezable liquid through a generallyfrost penetrable material having a surface exposed to an alfrescoenvironment experiencing below freezing temperatures, said constructioncomprising a utility pipe line located at a fixed depth below saidsurface where said liquid would normally freeze in such environment, asubstantially water impervious layer including a thermally insulatingplastic foam barrier material located continuously longitudinally andlaterally between said surface and said utility pipe line, said foambarrier material extending beyond opposite lateral sides of said utilitypipe line, said foam barrier material being selected of a thicknesssuflicient to prevent frost penetration to said utility pipe line for agiven degree-day environment thereby providing a frost-free Zonecompletely about said utility pipe line.

2. The construction of claim 1 wherein said frost penetrable materialcomprises earthen material.

3. The construction of claim 1 wherein said frost penetrable materialcomprises earthen material covered by a highway paving material.

4. The construction of claim 1 wherein said plastic foam barriermaterial comprises expanded polystyrene.

References Cited UNITED STATES PATENTS 2,602,764 8/1952 Billingham138-32 3,110,981 11/1963 Larner 52309 X 3,131,541 5/1964 Guthrie 6172.1X 3,276,213 /1966 Soesan 61-.5 X 3,279,334 10/1966 Quartararo 944 XFOREIGN PATENTS 10 429,706 2/ 1948 Italy.

921,844 3/ 1963 Great Britain.

OTHER REFERENCES EARL I. WITMER, Primary Examiner.

US. Cl. X.R.

